Gordon, now that you know that James Wade's father was William Wade, there might be a possibility of finding the correct family.
Widower James Wade stated at his Feb 1870 marriage that he was age 31, giving a birth year of 1838/9. Earlier, a 27 yr old James Wade had married Margaret Ellen Gaynor age 16 in Bellary, Madras, in July 1866, again giving a birth year of 1838/9 and a father's name of William. Then a 17 yr old Margaret Wade, wife of James Wade, died in Bellary in July 1867.
If you go back to a time before any modern research had been done into your Wade family, what is the source of the knowledge of Manx origins ? Is it entirely by word of mouth, or is there some written documentation (eg family bible) which mentions the Isle of Man ? When the baptismal details of an 1839 born James Wade (son of John Wade and Elizabeth teare) were acquired in 1952, have you any idea how this came about ? Could it be that your grandfather Cyril hired a professional researcher to find a James Wade b 1839 Isle of Man, based on knowledge of James's age when Cyril knew him, and a vague "Manx roots" story in the family ? Might William, rather than James, have been the last Manx-born Wade, or even William's father ? Any little scraps that you know could prove to be helpful.
Jean C